Liquid crystal displays (LCDs) are commonly used as display devices for equipment such as portable televisions and notebook computers. A typical LCD includes a plurality of LCD elements forming a plurality of rows and columns, each LCD including a pixel electrode and a common electrode with a portion of liquid crystal material disposed therebetween. The pixel electrodes may be directly driven by a driver located outside of the array, or each pixel element may be coupled to an individual thin-film transistor (TFT) formed near the pixel location, the TFT including an electrode for receiving a data signal from a data line and an electrode for controlling application of the data signal to the pixel electrode. These elements may be driven according to a number of techniques, including line inversion and dot inversion.
According to a line inversion approach, the voltages applied across elements of adjacent rows of LCD elements are inverted with respect to one another. The image quality produced by line inversion techniques may be acceptable for smaller displays, but when the size and resolution of the display is increased, for example, when the resolution approaches that of an XGA mode (1024.times.768 pixels) for a display of diagonal measure greater than 12.1 inches, crosstalk between elements may cause the image quality to degrade to an unacceptable level.
Crosstalk can be reduced by using a dot inversion technique to drive the LCD elements. According to a typical dot inversion technique, the voltages applied across adjacent elements are inverted with respect to one another, as conceptually illustrated in FIG. 1. For a typical LCD in which elements are scanned by horizontal rows, dot inversion typically involves driving data lines connected to adjacent columns of LCD elements with voltages having opposite polarities with respect to a common voltage applied to the common electrodes of the LCD elements.
FIG. 2 illustrates a typical layout of a conventional TFT LCD. A plurality of LCD elements PX are formed on a substrate in an array of rows and columns. A plurality of data lines D1-Dk are formed, a respective one of which lies between a respective pair of columns of LCD elements PX. For the TFT LCD elements, a plurality of gate lines G1-Gn are provided for controlling the application of data signals to the LCD elements PX from the data lines D1-Dk, using a respective TFT incorporated in a respective LCD element PX.
While driving such an array using a dot inversion approach can improve image quality in comparison to line inversion approaches, capacitance between LCD elements of a column and adjacent data lines which are not connected to the column of LCD elements can cause distortion of the data signals applied to the LCD element of an array such as the one illustrated in FIG. 2. Although the uniform structure of the array generally causes the distortion to be uniform across most of the array, the lack of a data line adjacent an outermost column Cl of the array can cause nonuniform behavior in the outermost column of elements Cl. This nonuniform behavior can result in nonuniform image quality.